5. FIELD OF THE INVENTION
The present invention relates to a data communication apparatus having a speech communication function and a data communication function.
2. Related Background Art
A facsimile system is known as an apparatus of this type. In the facsimile system, a telephone line is switched to the facsimile or telephone set side to perform image data communication or speech communication. When a start key in the facsimile system is depressed to perform image communication, the transmission line is switched from the telephone set to the facsimile system, and communication is started. In other words, in a conventional facsimile system, the start key must be depressed to start facsimile communication.
In recent years, there has become available is a communication system including one facsimile system and a plurality of telephone sets, all of which are commonly connected to a communication line. Examples of such a communication system are described in U.S. Ser. No. 108,915 (filed on Oct. 15, 1987) and U.S. Ser. No. 106,783 (filed on Oct. 13, 1987) by the present applicant. In the above-mentioned system, a plurality of operators share one facsimile system, and therefore, the facsimile system is located at a place remote from the telephone sets (i.e., operators). For this reason, U.S. Ser. No. 108,915 describes an arrangement in which a facsimile system can be operated from each telephone set, and U.S. Ser. No. 106,783 describes an arrangement in which an operating state of a facsimile system is displayed on each telephone set. In a communication system in which, particularly, one facsimile system and a plurality of telephone sets share a communication line, since the facsimile system must be operated at a remote area, it is inconvenient for each operator to operate the start key of the remote facsimile system every time image communication is required. Prior art systems in which a plurality of telephone sets and a facsimile system are selectively switched with respect to a plurality of communication lines are described in U.S. Ser. No. 813,514 (filed on Dec. 26, 1985) and U.S. Pat. No. 823,286 filed on Jan. 28, 1986). Arrangements in which the number of keys in the facsimile system is decreased are described in U.S. Pat. No. 4,502,080 and U.S. Pat. No 4,567,322. U.S. Pat. No. 4,502,080 describes an arrangement in which transmission, reception, and copying can be selectively performed by a single key. U.S. Pat. No. 4,567,322 describes an arrangement in which transmission, reception, copying, and recording paper cutting can be performed by a single key.